1. Field of the Invention
This invention relates to pivotal and slideable bottom edge supports for article shipping racks.
2. Discussion of the Prior Art
Articles, e.g., automotive lites such as windshields or backlites, are shipped in racks in a generally vertical position with the bottom edge of the articles supported on rubber bottom edge supports mounted on the base of the rack. Examples of shipping racks are taught in U.S. Pat. Nos. 3,533,502 and 3,809,234.
During shipment of the automotive windshields, maximum surface contact between the article edge and the bottom edge support is desired. This is because a mismatch between the curvature of the support edge of the article and the bottom edge support sets up point contact stress that can cause the windshields to fracture during shipping or handling of the loaded rack. Further, during shipment, transportation forces act to move the articles along a longitudinal path parallel to the backwall against end restraints. When there is only point contact between the article edges and the bottom edge supports, there is little or no frictional forces acting on the article edges to counteract the longitudinal transportation forces.
In the prior art, the above problems could be overcome by providing bottom edge supports having a surface curvature to match the peripheral edge contour of the articles to be shipped. This is expensive because different types of bottom edge supports have to be stored and mounted on the base of the rack for each change of article configuration.
In U.S. Pat. No. 3,519,244, there is taught a wooden shipping crate having a support for supporting the articles at their major surfaces. In general, the support includes an outer shell, main frame and inner support elements, each of which is formed from a rectangular piece of corrigated cardboard by providing a series of integral, flexible hinge lines in the rectangular sheets and by attaching a portion of the outer shell to the main frame. This type of edge support is not reusable and therefore is not of the type recommended for returnable article shipping racks. Further because the supports are made of cardboard they are not readily adaptable for supporting articles at their edges. This is because the edges of the articles cut into the cardboard supports collapsing them.
It would be advantageous therefor if a bottom edge support for returnable shipping racks was available that could be used with articles having different peripheral contours while providing maximum surface contact to eliminate point contact stress and to increase frictional engagement between the articles and the bottom edge supports to minimize longitudinal movement of the articles during shipping.